Next generation or “5G” telecommunications technology represents a giant leap forward in both requirements and resources. In terms of resources, it is expected that 5G may have access to frequency bands from under 6 GHz (where the current Long Term Evolution (LTE) frequency bands are) up to 100 GHz. In terms of requirements, three 5G categories are often discussed:                enhanced mobile broadband (eMBB), requiring very high data rates and large bandwidths;        Ultra-reliable low latency communications (URLLC), requiring very low latency, and very high reliability and availability; and        Massive machine type communications (mMTC), requiring low bandwidth, high connectivity, enhanced coverage, and low energy consumption on the user end.        
One aspect of the 5G technologies are the changes to the physical layer, in which, as mentioned above, the 5G technology is often referred to as NR. Numerology (i.e., waveform parameters, such as the cyclic prefix (CP) and subcarrier spacing) is presently a non-issue because, under LTE, there is only one numerology in which, for example, the subcarrier spacing (SCS) is always 15 kHz. In such a radio environment, it is a relatively simple task for a user equipment (UE) to roughly synchronize with the signal and, based on their preset mapping in the frequency domain, find the primary synchronization signals (PSSs) and secondary synchronization signals (SSSs) in the time domain to fully synchronize.
On the other hand, because of the range of 5G requirements, NR must have multiple numerologies in order to encompass the range of usage (from relatively low bandwidth, like mMTC, to extremely high bandwidth, like 4K video on eMBB) and possible frequency bands (from sub-6 GHz up to 100 GHz, which includes, for example, millimeter-wavelength bands at around 30 GHz). In practice, this means, for example, there may be multiple SCSs, such as, for example, 15 kHz, 30 kHz, and 60 kHz, of three different numerologies transmitting at the same time and on at least partially overlapping frequency bands.
Thus, a UE in 5G NR must be able to determine, isolate, and synchronize to more than one numerology—a new requirement for the UE.